The invention relates to a connection assembly of a turbine housing with a bearing housing of an exhaust gas turbocharger and to an exhaust gas turbocharger including such a connection assembly.
Such a connection assembly is already known and is shown in FIG. 1. FIG. 1 shows a known connection assembly 10 of a turbine housing 14 to a bearing housing 12 of an exhaust gas turbocharger. The turbine housing 14 is thereby centered on the bearing housing 12 by means of a centering collar 21.
When connecting the two housings by means of a V collar clamp 16, a connection joint 19 is obtained, which of course needs a seal.
The sealing of the connection joint 19 is realized in such a manner that the turbine housing 14 and the bearing housing 12 form, together with a heat shield 18, a sealing assembly 20, whereby a discharge to the environment of an exhaust gas driving a turbine, not shown, in the turbine housing is prevented.
In FIGS. 1A, 1B, this sealing assembly between the turbine housing 14, the bearing housing 12 and the heat shield 18 is indicated by the reference numeral 20. By means of the shown sealing assembly 20, a positioning of the heat shield 18 is also realized by an axial and radial abutment at the turbine housing 14.
The heat shield 18 further has the purpose to avoid or to at least reduce an excessive heat transfer from the hot exhaust gas flowing through the turbine housing 14 to the bearing housing 12.
Due to the fact that the bearing housing 12 is manufactured of cast iron and the turbine housing 14 consists of steel, the turbine housing has a higher heat expansion coefficient. The disadvantage of the state of the art shown in FIG. 1 is the result of the different heat expansion coefficients causing different heat expansion of the two housings.
Due to the positioning of the heat shield 18 displaced in the axial direction towards the turbine housing 14, whereby the sealing assembly 20 is not arranged centrally with regard to the V collar clamp 16, a gap can occur at extreme temperature differences due to the different heat expansions, which the V collar clamp can only compensate for insufficiently or not at all. The result can be a gas leak, and exhaust gases can pass from the exhaust gas turbocharger to the environment.
The different heat expansions of the housings are further increased in that the turbine housing 14 is heated to a greater degree than the bearing housing 12 due to the in favorable positioning of the heat shield 18.
Furthermore, due to this higher heat entry, the surfaces of the heat shield 18 in contact in the sealing assembly 20 may be warped, which results in a gas leak.
It is the object of the present invention to provide a connection assembly of the above-mentioned type in such a manner that a gas leak is avoided and that a centering of the two housings relative to each other is simultaneously achieved.